Permo-Triassic reconstruction of Western Pangea and the evolution of the Gulf of Mexico-Caribbean region

A Permo-Triassic reconstruction of western Pangea (North America, South America, Africa) is proposed that is characterized by: 1) definition of the North Atlantic fit by matching of marginal offsets (fracture zones) along the opposing margins, 2) a South Atlantic fit that is tighter than the Bullard fit and that is achieved by treating Africa as two plates astride the Benue Trough and related structures during the Cretaceous, 3) complete closure of the Proto-Atlantic Ocean between North and South America, accomplished by placing the Yucatan block between the Ouachita Mountains and Venezuela, 4) a proposed Hercynian suture zone that separates zones of foreland thrusting from zones of arc-related magmatic activity; to the northwest of this suture lie the Chortis block and Mexico and most of North America, and to the southeast of this suture lie South America, the Yucatan block, Florida and Africa, and 5) satisfaction of paleomagnetic data from North America, South America and Africa. Beginning with the proposed reconstruction, the relative motion history of South America with respect to North America is defined using the finite difference method. Within the framework provided by the proposed relative motion history, an evolutionary model for the development of the Gulf of Mexico and Caribbean region is outlined in a series of 13 plate boundary reconstructions at various time intervals from the Jurassic to the present. The model includes: 1) formation of the Gulf of Mexico by 140ma, 2) Pacific provenance of the Caribbean plate through the North America-South America gap during Cretaceous time, 3) Paleocene-Early Eocene back-arc spreading origin for the Yucatan Basin, whereby Cuba is the frontal arc and the Nicaragua Rise-Jamaica is the remnant arc, and 4) 1400 km of post-Eocene cumulative offset along both the Northern and Southern Caribbean Plate Boundary Zones, allowing grandiose eastward migration of the Caribbean plate with respect to the North and South American plates

Plate-tectonic evolution of the Gulf of Mexico and Caribbean region

A geologic- kinematic model for the evolution of the Gulf of Mexico and Caribbean region is built within a framework provided by a detailed Late Paleozoic (Alleghenian) plate reconstruction and a revised North American (NOAM) and South American (SOAM) relative motion history. From the Middle Jurassic to the Campanian, SOAM migrated east-southeast from NOAM. From the Carapanian to the Eocene. Little or no NOAM-SOAM relative motion occurred, although minor sinistral transpression is suggested. Since the Eocene, minor west-northwest convergence between NOAM and SOAM has occurred along pre-existing fracture zones. Three stages of evolution are recognized which correlate with these phases of relative motion. Stage 1: mainly carbonate shelves fringed the Gulf of Mexico and "Proto-Caribbean" passive rifted margins, during plate separation. Stage 2: the Caribbean Plate (CARIB) progressively entered the NOAM-SOAM gap from the Pacific by subduction of Proto-Caribbean crust beneath the Greater Antilles, Stage 3: CARIB migrated east by 1200 km, subducting Proto-Caribbean crust and forming the Lesser Antilles Arc, Transform faults have dissected the original Greater Antilles Arc, and nappes in the Venezuelan Andes have been emplaced southeastwards onto the northern SOAM margin, diachronously from west to east. Field work done in Dominican Republic, both near Puerto Plata and in the southwest sector, indicates that 1) Cuba and northern and central Hispaniola are parts of one original Greater Antilles arc, 2) this arc collided with the Bahamas in the Late Paleocene=Mid Eocene, and 3) Hispaniola has been assembled by strike-slip juxtaposition of terranes from the west

In Vindication of Justiciable Victims\u27 Rights to Truth and Justice for State-Sponsored Crimes

In this Article, Professor Aldana-Pindell explores the norms establishing a state\u27s responsibility to grant victims of human rights violations adequate rights in the criminal prosecution process as a remedy for their victimization. She argues that victim-focused prosecution norms comport and provide more effective means of promoting respect for human rights, in certain nations in democratic transition from mass atrocities. Moreover, she suggests that, as part of other justice reforms, states plagued with impunity should adopt criminal procedures granting surviving human rights victims greater standing in the prosecution process. Professor Aldana-Pindell then uses Guatemala to examine the factors that compel the need for reformed victim\u27s rights in a country whose criminal justice system is wrought with incompetence and corruption

Teaching Social Justice, Expanding Access to Justice: An Introduction

Teaching Social Justice, Expanding Access to Justice: An Introduction provides an introduction to the publications in this issue focusing on the need for a change in legal education to promote the moral and ethical obligation of providing affordable and accessible legal services. The article introduces this issues\u27 publications which all support the underlying theme of providing social justice to the underprivileged by making legal services accessible or reforming legal education to promote a new generation of attorneys with an underlying passion for fostering affordable and accessible public service

Public Eco-art: Interdisciplinary Art/Science collaborations shift cultural attitudes while implementing science-based solutions

Public Eco-art brings Art, Science, Technology, and Community together to achieve environmental solutions ... while multiplying sources of funding and support! The Salish Sea region is home to several impressive Eco-art initiatives that bring water-quality out of the water-closet and into the cultural mainstream. This talk will offer examples and resources for organizational or individual collaborations

U-Pb Geochronology of detrital zircons from the Venezuelan passive margin : implications for an Early Cretaceous Proto-Orinoco river system and Proto-Caribbean ocean basin paleogeography

The Guyana Shield has long been interpreted as the source of siliciclastic detritus within the Cretaceous passive margin strata of northern Venezuela. We have determined U-Pb ages of detrital zircons separated from Early Cretaceous strata of the passive margin. Although the Guyana shield is the probable source for much of the Archean, Paleoproterozoic and early Mesoproterozoic detrital zircon grains, there is a prominent age population (ca.0.95-1.2Ga) that is not easily explained as being derived from the shield. A western source in the Venezuelan and/or northern Colombian Andes is suggested for this detrital component. We propose that a Proto-Orinoco river system drained both the Guyana Shield and the Venezuelan and Colombian Andes and that branches of this river system were funneled through Triassic/Jurassic rift basins that formed during initial opening of the Proto- Caribbean Seaway. The detrital zircon age data have implications for paleogeographic reconstructions of the Caribbean region prior to the breakup of Pangea and the longevity of continental scale river systems

Foundations of Gulf of Mexico and Caribbean evolution : eight controversies resolved

Eight points of recurring controversy regarding the primary foundations of models of Gulf of Mexico and Caribbean tectonic evolution are identified and examined. The eight points are controversial mainly because of the disconnect between different scales of thinking by different workers, a common but unfortunate problem in the geological profession. Large-scale thinkers often are unaware of local geological detail, and local-scale workers fail to appreciate the level of evolutionary precision and constraint provided by regional tectonics and plate kinematics. The eight controversies are: (1) the degree of freedom in the Gulf-Caribbean kinematic framework that is allowed by Atlantic opening parameters; (2) the existence of a South Bahamas-Guyana Transform, and the role of this structure in Cuban, Bahamian, Trinidadian, and Guyanese evolution; (3) the anticlockwise rotation of the Yucatán Block during the opening of the Gulf of Mexico; (4) the Pacific origin of the Caribbean oceanic crust; (5) the Aptian age and plate boundary geometry of the onset of west-dipping subduction of Proto-Caribbean beneath Caribbean lithospheres; (6) the origin and causal mechanism of the Caribbean Large Igneous Province…not Galapagos!; (7) the number and origin of magmatic arcs in the northern Caribbean; and (8) the origin of Paleogene "flysch" deposits along northern South America: the Proto-Caribbean subduction zone. Here we show that there are viable marriages between the larger and finer scale data sets that define working and testable elements of the region's evolution. In our opinion, these marriages are geologically accurate and suggest that they should form discrete elements that can and be integrated into regional models of Gulf and Caribbean evolution. We also call upon different facets of the geological community to collaborate and integrate diverse data sets more openly, in the hopes of improving general understanding and limiting the publication of unnecessary papers which only serve to spread geological uncertainty

Evolution of seaward-dipping reflectors at the onset of oceanic crust formation at volcanic passive margins: Insights from the South Atlantic

Seaward-dipping reflectors (SDRs) have long been recognized as a ubiquitous feature of volcanic passive margins, yet their evolution is much debated, and even the subject of the nature of the underlying crust is contentious. This uncertainty significantly restricts our understanding of continental breakup and ocean basin–forming processes. Using high-fidelity reflection data from offshore Argentina, we observe that the crust containing the SDRs has similarities to oceanic crust, albeit with a larger proportion of extrusive volcanics, variably interbedded with sediments. Densities derived from gravity modeling are compatible with the presence of magmatic crust beneath the outer SDRs. When these SDR packages are restored to synemplacement geometry we observe that they thicken into the basin axis with a nonfaulted, diffuse termination, which we associate with dikes intruding into initially horizontal volcanics. Our model for SDR formation invokes progressive rotation of these horizontal volcanics by subsidence driven by isostasy in the center of the evolving SDR depocenter as continental lithosphere is replaced by more dense oceanic lithosphere. The entire system records the migration of >10-km-thick new magmatic crust away from a rapidly subsiding but subaerial incipient spreading center at rates typical of slow oceanic spreading processes. Our model for new magmatic crust can explain SDR formation on magma-rich margins globally, but the estimated crustal thickness requires elevated mantle temperatures for their formation